BR112013003572B1 - INVERSION APPLIANCE AND INVERSION CONTROL METHOD - Google Patents

Abstract

inversion apparatus and inversion control method. an inverter device basically includes an inverter (3), a rotational speed detection component (12, 26, 27) and a control component (9). the inverter (3) includes a plurality of pairs of switching elements (q1 to a6). the control component (9) controls the on-off state of the switching elements (q1 to q6) to convert a direct current from a direct current energy source (!) into an alternating current by alternately executing the first and the second control when the rotational speed of the motor (4) connected to the switching elements is greater than the prescribed rotational speed. the first control turns on the switching elements (q1, q3.q5) that are directly connected to a positive electrode of the power source, and turns off the switching elements (q2.q4.q6) that are directly connected to a negative electrode of the power source power supply. the second control turns on the switching elements (q2, q4, q6) that are directly connected to a negative electrode and turns off the switching elements (q1, q3, q5) that are directly connected to a positive electrode.

Description

“INVERSION APPLIANCE AND INVERSION CONTROL METHOD”

CROSS REFERENCE WITH RELATED REQUESTS

This application claims the priority of Japanese Patent Application No. 2010206775, filed on September 15, 2010. The entire disclosure of Japanese Patent Application No. 2010-206775 is incorporated here for reference.

BACKGROUND

Field of the Invention

The present invention generally relates to an inversion apparatus and an inversion control method.

Information Background

An apparatus with a conventional drive motor may include an electrical energy storage device, an inverter circuit and a plurality of switching elements that are provided between the electrical energy storage device and the inverter circuit. The switching elements are operated by a controller to connect and disconnect an electrical power supply between the electrical energy storage device and a motor. An example of a conventionally powered engine is disclosed in Japanese Patent Publication made available to the public No. 2005-39887. In this publication, the motor drive device enables an exchange of electrical energy between the electrical energy storage device and the motor. When the rotational speed of the motor is equal to or greater than the prescribed rotational speed, all switching elements of the reversing circuit that are connected to a positive electrode of the electrical energy storage device or all switching elements of the reversing circuit that are connected to a negative electrode of the electrical energy storage device are closed (in a conductive state). However, when an electric current flowing to the switching elements goes to zero, the switching elements are placed in a disconnected or non-conducting state.

SUMMARY

It has been found that with the conventional motor drive device discussed above, when the rotational speed of the motor is equal to or greater than the prescribed rotational speed, a control is performed so that only all the switching elements connected to a positive electrode of the electrical energy storage device when only all the switching elements connected to a negative electrode of the electrical energy storage device are closed. This control is performed until the current flowing to the switching elements goes to zero. Consequently, the electric current flows to the switching elements in an unbalanced manner and the service life of the switching elements is shortened.

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An object of the present disclosure is to provide an inverter device that enables an extension of the service life of the switching elements.

In view of the state of the art, an aspect of the present disclosure is to provide an inverter apparatus which basically comprises an inverter, a rotational speed detection component and a control component. The inverter includes a plurality of pairs of switching elements. Each of the switching element pairs is electrically connected to a direct energy current. The rotational speed detection component detects a rotational speed of a motor that is electrically connected to the pairs of switching elements. The control elements control an on-off state of the switching elements to convert a direct electric current from the direct electric current source to an alternating electric current. The control component also performs alternately a first switching control and a second switching control by detecting the rotational speed being greater than the prescribed rotational speed. The first switching control connects all other switching elements of the switching element pairs connected to a positive electrode of the direct electric power source, and disconnects all other switching elements of the switching element pairs connected to a negative electrode of the direct electric power source. The second switching control connects all other switching elements of the switching element pairs connected to a negative electrode of the direct electric power source, and disconnects all other switching elements of the switching element pairs connected to a positive electrode of the direct electric power source.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings that form a part of the original disclosure:

Figure 1 is a block diagram of a power source drive device that includes an inverter device according to an embodiment;

Figure 2 is a block diagram of the motor controller shown in Figure 1;

Figure 3 is a graph showing a rotational speed limit value versus a voltage characteristic for a capacitor shown in figure 1;

Figure 4 is a graph showing the time characteristics of individual door activation signals from the switching elements and a time characteristic of an electric current flowing from the inverter towards the battery;

Figure 5 is a graph showing a temperature against a frequency characteristic of door trigger signals for the switching elements;

Figure 6 is a flowchart showing a control procedure for an inverter device shown in Figure 1; and

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Figure 7 is a graph showing a battery charging / discharging energy versus a switching frequency characteristic for the inverter device shown in figure 1.

DETAILED DESCRIPTION OF THE MODALITIES

The selected modalities will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the modalities are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

Referring initially to figure 1, a power source device is schematically illustrated for an electric vehicle that includes an inverter device according to a first embodiment. The electric vehicle of this modality includes, among other things, a battery 1, a relay 2, an inverter 3 and a permanent magnetic motor 4. The inverter 3 includes a plurality of switching elements Q1 to Q6 (example, bipolar transistors with isolated port IGBT) and a plurality of rectifying elements D1 to D6 (example, diodes). With the inverter apparatus disclosed here, the electric current flowing to the inverter 3 is distributed to substantially evenly between the switching elements Q1 to Q6. As a result, the electric current can be prevented from flowing to the switching elements Q1 to Q6 in an unbalanced manner and the service life of the switching elements Q1 to Q6 can be extended. Also discussed below, inverter 3 still includes a capacitor 5, a resistor 6, a voltage sensor 7 and a door drive circuit 8.

Although a detailed design is not provided, the electric vehicle's permanent magnetic motor 4 in this illustrated embodiment operates on a three-phase AC power that serves as a source of drive power in a conventional manner. The motor 4 is connected to a wheel axle of the electric vehicle in a conventional manner to provide a driving force for one or more wheels. Although an electric vehicle will be used as an example, an inverter device can also be applied to a hybrid vehicle (HEV).

In addition, the components mentioned above, the electric vehicle of this modality still includes an engine controller 9, a vehicle controller 10, a plurality of electric current sensors 11 and a rotation position sensor 12. These serve as a power source electrical for motor 4. Battery 1 is connected to inverter 3 via relay 2. Inverter 3 is configured to convert the DC energy of battery 1 into AC energy. Battery 1 includes, for example, a plurality of lithium ion batteries or other types of secondary battery. Relay 2 is opened and closed by vehicle controller 11 in coordination with an on / off operation of a vehicle's ignition key switch (not shown). Specifically, relay 2 is closed when the

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4/15 ignition (not shown) is turned on, and relay 2 is opened when the ignition key switch (not shown) is turned off.

The rectifying elements D1 to D6 are connected in parallel with each of the switching elements Q1 to Q6. The rectifying elements D1 to D6 are configured so that the electric current flowing there in a direction opposite to a direction in which the electric current flows in the switching elements Q1 to Q6. Inverter 3 converts DC power from battery 1 into AC power and supplies AC power to motor 4. In this mode, three circuits comprising a pair of (two) switching elements connected in series are connected to battery 1 in parallel to each other other. Each of the three input sections of the three-phase motor 4 is also electrically connected between the two switching elements of a pair of switching elements. The same type of switching element is used for all switching elements Q1 to Q6. For example, a bipolar isolated port transistor (IGBT) can be used for each of the switching elements Q1 to Q6.

As shown in figure 1, in this illustrative embodiment, the switching elements Q1 to Q6 are connected together in series, the switching elements Q3 and Q4 are connected together in series, and the switching components Q5 and Q6 are connected together in series. The U phase of motor 4 is connected between the switching elements Q1 to Q2. The V phase of motor 4 is connected between the switching elements Q3 and Q4. The W phase of motor 4 is connected between the switching elements Q5 and Q6. The switching elements Q1, Q3 and Q5 are electrically connected to a positive battery electrode and the switching elements Q2, Q4 and Q6 are electrically connected to a negative battery electrode 1. The on / off state of each of the elements switching parameters Q1 to Q6 are controlled by a vehicle controller 10. The operation of the switching elements Q1 to Q6 performed by vehicle controller 10 will be explained in more detail later.

In the inverter 3, capacitor 5, resistor 6, and voltage sensor 7 are connected between relay 2 and switching elements Q1 to Q6. Capacitor 5 is provided to soften the DC electrical energy supplied from battery 1. Voltage sensor 7 is used to detect the voltage through capacitor 5. Port drive circuit 8 is used to send a door signal to each of the control elements. switching Q1 to Q6 and switching the switching elements Q1 to Q6 on and off. Door drive circuit 8 detects overheating and overload abnormalities in switching elements Q1 to Q6. Based on these detections, door drive circuit 8 sends an abnormal signal to motor controller 9. Door drive circuit 8 also receives a signal from voltage sensor 7 and converts the signal to a waveform level which can be recognized by the motor controller 9 before sending the signal to the controller

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5/15 of motor 9 as a signal indicating a voltage of capacitor 5.

The motor controller 9 controls the inverter 3 and the operation of the motor 4. The motor controller 9 constitutes a control component or means. The motor controller 9 receives a signal indicating a torque command value (T *) emitted from the vehicle controller 10, a signal from the rotor positioning sensor 12, response signals from the electric current sensors 11 and a sensor signal voltage 7. Motor controller 9 generates a PWM (pulse width modulation) signal according to the signals received from these sensors and controller vehicle 10. Motor control 9 sends the PWM signal to the door drive circuit 8. The door drive circuit 8 switches the switching elements Q1 to Q6 on and off in a prescribed time based on the pulse width modulation signal.

Vehicle controller 10 includes a central processing unit (CPU), a read-only memory (ROM), and a random access memory (RAM). Vehicle controller 10 serves as a control section for controlling the entire vehicle in this mode. Vehicle controller 10 calculates a torque command value (T *) based on an accelerator signal, a brake signal, and a shift signal and sends the torque command value (T *) to the engine controller 9. Vehicle controller 10 also sends a start request command to engine controller 9 after determining that the vehicle will start, and sends a stop request command to engine controller 9 after determining that the vehicle will be stopped. Vehicle controller 10 also sends open / closed status information in relation to relay 2 to motor controller 9.

The electric current sensors 11 are arranged between the inverter 3 and the motor in relation to each of the respective phases of the motor 4. The electric current sensors 11 are used to detect the electric currents (Iu, Iv, Iw) supplied to each one. of the motor 4 phases from the inverter 3. The electric current sensors 11 send signals indicating the detected electric currents to the motor controller 9. The rotor positioning sensor 12 is a resolution, an encoder, or other sensor device that it is provided in the motor 4 and serves to detect a rotor position for the motor controller 9. The rotor position sensor 12 sends a detected position of the rotor to the motor controller 9.

The constituent characteristics of motor controller 9 will now be explained in more detail with reference to figure 2. Figure 2 is a block diagram of motor controller 9 included in the inverter according to this modality. As shown in figure 2, the motor controller 9 comprises a section calculating the electric current command value 21, a section of electric current control 22, a section converting from dq to three-phase 23, a section generating a PWM signal 24 , a section of

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6/15 conversion from three-phase to dq 25, a phase computing section 26, a rotational speed computing section 27 and a pseudo three-phase short circuit control section 28. The rotor positioning sensor 12, the computing section phase 26 and rotational speed computing section 27 constitute a rotational speed detection component or medium.

The electric current command value calculation section 21 receives the torque command value (T *), an angular speed (ω) of the motor 8 calculated by the rotational speed computing section 27, and a detected voltage (Vdc) of capacitor 5 detected by voltage sensor 7. The electric current command value calculation section 21 refers to a map to calculate a pair of electric current command values of dq axis (i * d, i * q ) indicating a target value of an alternating current supplied to motor 4 from an inverter 3. The map uses a torque command value (T *), angular speed (ω) and voltage (Vdc) as indices. The map is stored in the electric current command value calculation section 21 in advance to determine the electric current command values for the dq axis (i * d, i * q). The map is configured to output an optimal command value to minimize a loss from drive 3 and a loss from motor 4 for a given input configuration. The d and q axis values indicate coordinates in the polar coordinate system.

The electric current control section 22 receives the electric current command values from the dq axis (i * d, i * q) and a pair of electric currents from the dq axis (id, iq) transmitted from the three-phase to dq conversion section 25 and computes a pair of dq axis voltage command values (V * d, V * q). the electrical current control section 22 also sets the voltage command values of the dq axis (V * d, V * q) to zero when it receives a switching signal Vd * Vq * from the pseudo three-phase short circuit control section 28 .

The dq to three-phase conversion section 23 receives the axis voltage command values dq (V * d, V * q) and a phase detection value (θ) from the phase computing section 26 and converts the values of axis voltage command dq (V * d, V * q) in a polar coordinate system for a configuration of voltage command values (V * u, V * v, V * w) in a fixed coordinate system having a u-axis, a v-axis and a w-axis. The dq to three-phase conversion section 23 produces the voltage command values (V * u, V * v, V * w) resulting from conversion to the PWM signal generation section 24.

The PWM signal generation section 24 generates a PWM signal to control the switching of the switching elements Q1 to Q6 based on the detected voltage (Vdc) of capacitor 5 and the voltage command values (V * u, V * v, V * w) and sends the PWM signals to the inverter 3. When the PWM signal generation section 24 receives a PWM switching signal from the three-phase short circuit control pseudo section 28, the PWM signal generation section 24 sends a signal PWM shown in figure 4 (explained later).

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The three-phase to dq 25 conversion section is a control section used to convert from three-phase to two-phase. It receives phase currents (iu, iv, ei _w ) and a detected phase value (θ) from the phase computing section 26 and converts the phase currents (iu, iv, iw) indicated in the coordinates set for the current currents. phase (id, iq) indicated in the polar coordinates. The three-phase to dq 25 conversion section also sends the phase currents (id, iq) indicated in the polar coordinates resulting from the conversion to the electric current control section 22.

The phase computing section 26 computes the rotor phase (θ) based on a signal from the rotor position sensor 12 indicating a position of the sent rotor 4 and sending the computed phase (θ) to the dq conversion section for three-phase 23, the three-phase to dq 25 conversion section and the rotational speed computing section 27. The rotational speed computing section 27 computes a rotational speed (electrically angular velocity) (ω) differentiating the phase (θ) and sends the angular velocity computed for the electric current command value calculation section 21 and the short circuit control pseudo section 28.

The pseudo three-phase short circuit control section 28 determines whether to electrically disconnect motor 4 from battery 1 (DC power source) based on the detected voltage (Vdc) of capacitor 5, the axis voltage command values dq (V * d, V * q), and a rotational speed (ω). Based on the determination results, the pseudo three-phase short circuit control section 28 generates a switching signal Vd * -Vq * and a switching signal PWM and sends the switching signal Vd * -Vq * to the control section of electric current 22 and the PWM switching signal for the PWM signal generation section 24.

During torque control of motor 4, there is a possibility that the rotational speed of motor 4 will increase to a point where the output voltage of the inverter reaches a saturation level and an appropriate electrical current target value cannot be configured. When this occurs, the control of the torque command value becomes unstable and there is a possibility that the vehicle's behavior will become unstable.

At this moment, as will be explained now, a control is performed to suppress the rotational speed of the motor 4 for a rotational speed equal to or less than the prescribed limit speed when the rotational speed of the motor 4 has exceeded the prescribed limit value. In addition, in order to prevent the electric current flowing in the inverter 3 from being concentrated in certain switching elements between the switching elements Q1 to Q6 during rotational speed suppression control, the pseudo three-phase short circuit control section 28 performs a control to distribute the current of electricity flowing to the inverter 3 between the switching elements Q1 to Q6.

The control of the inversion device according to this modality will now be described using figures 3 to 5. Figure 3 is a graph showing a limit value of speed

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8/15 rotational city versus voltage characteristic for capacitor 5. Figure 4 and a graph showing the time characteristics of the door activation signals of switching elements Q1 to Q6 and a time characteristic of an electric current flowing from the inverter 3 towards battery 1. Figure 5 is a graph showing the temperature versus the door trigger signal frequency characteristic for the switching elements Q1 to Q6.

The pseudo three-phase short circuit control section 28 has a rotational speed limit value (ω ^ set here as a limit value to determine an inverter control state 3. If a rotational speed of motor 4 is greater, then a voltage of motor-induced backwards 4 becomes greater. However, if the capacitor voltage is low, then the control becomes unstable, so when the rotational speed (ω) computed by the rotational speed computing section 27 becomes greater than the rotational speed limit value (ωο), the pseudo three-phase short circuit control section 28 determines that there is a possibility of controlling instability.

The pseudo three-phase short circuit control section 28 sets the rotational speed limit value (ω ^ based on the detected voltage (Vdc) through capacitor 5. Even if the back voltage induced by motor 4 is high, the voltage difference between the input and output sides of inverter 3 will be lower and the control state of inverter 3 will be stable if the detected voltage (Vdc) of capacitor 5 is higher, therefore the rotational speed limit value (ω ^ is set to a higher value when the detected voltage (Vdc) of capacitor 5 is higher, and the rotational speed limit value (ω ^ is set to a lower value when the detected voltage (Vdc) of capacitor 5 is lower. Thus, as shown in figure 3, the rotational speed limit value (ωφ is proportional to the detected voltage of capacitor 5 and the pseudo three-phase short circuit control section 28 sets the rotational speed limit value (ω ^ being greater than with the highest detected voltages (Vdc) of capacitor 5.

In addition, to determine a control state based on the rotational speed (ω), the pseudo three-phase short circuit control section 28 determines a control state based on a percentage modulation of the inverter 3. The pseudo control section of the inverter three-phase short circuit 28 first calculates the percentage modulation (M) based on the voltage (Vdc) detected by the voltage sensor 7 and an axis voltage command value dq (V * d, V * q) from the control section of electric current 22 using equation (1) shown below.

Percentage modulation (M) indicates a range of a voltage supplied to the

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9/15 motor 4 for a DC voltage of battery 1. It is known that when the percentage modulation (M) exceeds 1, the voltage waveform supplied to motor 4 is not sinusoidal, but is instead distorted.

The three-phase short circuit control section 28 sets a prescribed percentage modulation threshold (Mc) to determine an inverter control state 3. The three-phase short circuit control section 28 determines that the control state can be unstable if the calculated percentage modulation (M) is higher than the percentage modulation limit value (Mc).

When the rotational speed (ω) is greater than the rotational speed limit value (ωο) and the percentage modulation M is higher than the percentage modulation limit value (Mc), the pseudo short circuit control section three-phase 28 transmits a switching signal Vd * Vq * to the electrical current control section 22 and performs a control to cause the axis voltage command values dq (V * d, V * q) to converge to zero. When the electric current control section 22 receives the switching signal Vd * Vq *, the electric current control section 22 stops following the received electric current command values (i * d, i * q) and the electric currents dq (id, iq) and gradually transitions the axis voltage command values dq (V * d, V * q) to zero. An example of a method for gradually transitioning the dq axis voltage command values (V * d, V * q) to zero is to apply a low step filter processing to the voltage command value using a command value of axis voltage dq (V * d, V * q) existing just before the switching signal Vd * Vq * was received.

When the axis voltage command values dq (V * d, V * q) have been converged to zero, the pseudo three-phase short circuit control section 28 sends a PWM switching signal to the PWM signal generation section 24 and performs a control in such a way that the resulting electric current from the regenerative control of the motor 4 is prevented from flowing only to certain switching elements between the switching elements Q1 to Q6 in an unbalanced manner.

When the PWM signal generation section 24 receives the PWM switching signal, the PWM signal generation section 24 alternately performs a control to switch on the switching elements Q1, Q3 and Q5 connected to the positive side of the battery 1 and switching off the elements switching devices Q2, Q4 and Q6 connected to the negative side of battery 1 (hereinafter referred to as a “first switching control”) and a control for switching on switching elements Q2, Q4 and Q6 and switching off switching elements Q1, Q3 and Q5 (hereinafter referred to as a “second switching control”).

Thus, as shown in figure 3, the periods during which the switching elements Q1, Q3 and Q5 are connected and the periods during which the switching elements Q2, Q4 and Q6 are connected do not overlap. Switching elements

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Q2, Q4 and Q6 are switched off during periods when switching elements Q1, Q3 and Q5 are switched on and elements Q1, Q3 and Q5 are switched off during periods when switching elements Q2, Q4 and Q6 are switched on. In figure 4, the term T is a period of a door trigger signal and the term DT is a dead time. The cycle period in which each switching element Q1 to Q6 is switched on and off is the same and the phase difference is zero. The switch-off times (DT) during which all of the switching elements Q1 to Q6 are switched off are provided between the respective switch-on periods and the switch-off periods of the switching elements Q1 to Q6. Thus, the length of the periods during which the switching control is performed to switch on the switching elements Q1, Q3 and Q5 and switching off the switching elements Q2, Q4 and Q6 equal to the length of the periods during which the second control of switching is performed to switch on the switching elements Q2, Q4 and Q6 and switching off the switching elements Q1, Q3 and Q5. All off times are provided between executions of the switching control and executions of the second switching control.

A backflow current caused by a voltage induced by the motor 4 was between the motor 4 and the inverter 3 during the periods when the switching elements Q1, Q3 and Q5 are on and the periods when the switching elements Q2, Q4, and Q6 are on, that is, during periods other than during off times. As shown in figure 3, the reflux current flows from inverter 3 to battery 1, and acts as a regenerative electric current (Idc) during off times. When the reflux electric current flows through the inverter 3, the reflux electric current flows either through the switching elements Q1, Q3 and Q5 and not through the switching elements Q2, Q4 and Q6 or flows through the switching elements Q2, Q4 and Q6 and not via the switching elements Q1, Q3 and Q5. As a result, the reflux current does not just flow through a certain switching element unevenly and, instead, can be distributed to all of the switching elements Q1 to Q6.

The PWM signal generation section 24 receives a PWM switching signal and sets a frequency at which the switching elements Q1 to Q6 are switched on and off (hereinafter “switching frequency”) during the control of the switching elements Q1 to Q6 . As shown in figure 5, the switching frequency is set to a frequency that is within a range measuring from a frequency f1 to a frequency f2. The switching frequency corresponds to a frequency to which the inverter 3 switches frequently between a state in which the switching elements Q1, Q3 and Q5 are switched on simultaneously and a state in which the switching elements Q2, Q4 and Q6 are switched on simultaneously.

As shown in figure 5, the characteristic temperature curve of the elements

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11/15 switching Q1 to Q6 has a minimum at a switching frequency f0. If the switching frequency increases from the switching frequency f0, then the temperature of the switching elements Q1 to Q6 will increase because the switching loss increases while the switching frequency increases. However, if the switching frequency decreases from the switching frequency f0, then the switching loss is substantially zero and the conduction loss is increased. When the switching frequency decreases the temperature, the switching elements Q1 to Q6 pulse and the amplitude of the pulse increases the more the switching frequency decreases. Consequently, the temperature of the switching elements Q1 to Q6 increases when, once the switching frequencies decrease from the switching frequency f0.

In figure 5, the temperature of the switching element Tc corresponding to the switching frequency f1 and the switching frequency f2 is a permissible temperature at which the switching elements Q1 to Q6 can be ensured to operate properly. Consequently, in this mode, the PWM signal generation section is configured to set the switching frequency to a frequency between the frequency f1 and the frequency f2 to prevent the temperature of the switching elements Q1 to Q6 from exceeding the permissible temperature and a overheated state of being reached.

As explained above, when the rotational speed of motor 4 becomes greater than the rotational speed limit value, motor controller 9 performs a first switching control and a second switching control alternately with respect to switching elements Q1 to Q6 . However, when the rotational speed of motor 4 becomes equal to or less than the rotational speed limit value, motor controller 9 sets an electrical current target value in relation to a torque command value or other external internal input and generates a PWM signal in relation to switching elements Q1 to Q6 based on the target value of the electric current. In this way, motor controller 9 changes to normal or regular switching control in relation to switching elements Q1 to Q6.

A control procedure performed by the inverter device according to this modality will now be explained using figures 1, 2 and 6. Figure 6 is a flow chart showing a control procedure of the inverter device according to this modality.

In step S1, motor controller 9 uses the feature shown in figure 3 to set the rotational speed limit value (ωο) based on a voltage detected by voltage sensor 7. In step S2, motor controller 9 detects a rotational speed of motor 4 based on a signal from the motor position sensor 12. In step S3, motor controller 9 compares a detected rotational speed with the limit value of rotational speed (ωc). If the rotational speed (ω) is equal to or less

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12/15 than the rotational speed limit value (ωο), then the control process is finished. However, if the rotational speed (ω) is greater than the rotational speed limit value (ω ^), then motor controller 9 proceeds to step S4.

In step S4, motor controller 9 uses equation 1 to switch a percentage modulation (M) based on the voltage detected by voltage sensor 7 and the voltage command values (V8d, V * q) of the control section electric current 22. In step S5, motor controller 9 compares the percentage modulation (M) with the percentage modulation limit value (Mc). If the percentage modulation (M) is equal to or less than the percentage modulation limit value (Mc), then the control process is finished. However, if the percentage modulation (M) is greater than the percentage modulation limit value (Mc), then motor controller 9 proceeds with step S6.

In step S6, motor controller 9 turns on the switching signal of the three-phase short circuit control pseudo section 28. The three-phase short circuit control section 28 sends the switching signal Vd * Vq * to the control section of the electric current 22 and causes the axis voltage command values dq (V * d, V * q) to converge to zero. When motor controller 9 is causing the axis voltage command value dq (V * d, V * q) to converge to zero, motor controller 9 calculates the axis voltage command values dq (V * d, V * q) (step S7) and determines if the axis voltage command values dq (V * d, V * q) have reached zero (step S8). If the voltage command values d-q (V * d, V * q) have not reached zero, motor controller 9 returns to step S7. If the axis voltage command values dq (V * d, V * q) have reached zero, motor controller 9 proceeds with step S9.

In step S9, motor controller 9 turns on the PWM switching signal of the three-phase short circuit control pseudo section 28. The three-phase short circuit control pseudo section 28 sends the PWM switching signal to the electric current control section 22 and performs a first control switch and a second control switch in relation to the switching elements Q1 to Q6 in an alternating manner.

Motor controller 9 detects a rotational speed of motor 4 based on a signal from the rotor positioning sensor 12 (step S10) and compares the detected rotational speed to the rotational speed limit value (ω ^ (step S11). rotational speed (ω) is greater than the rotational speed limit value (w), then the motor controller returns to step S10 If the rotational speed (ω) is equal to or less than the rotational speed limit value (ω) ^, then the motor controller proceeds with step S12.

Motor controller 9 disconnects the PWM switching signal from the pseudo three-phase short circuit control section 28 (step S12), disconnects the switching signal Vd * Vq * from

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13/15 pseudo three-phase short circuit control section 28, and returns to a regular (normal) switching control ending the control sequence.

As explained above, in this mode, the first switching control and the second switching control are performed alternately when the rotational speed (ω) is greater than the rotational speed limit value (ωο). As a result, the rotational speed of the motor 4 can be suppressed and the current flowing in the inverter 3 can be evenly distributed on the switching elements Q1 to Q6. Thus, a situation in which only certain switching elements between switching elements Q1 to Q6 reach a high temperature and can prevent them from incurring large switching losses. As a result, control of inverter 3 can be stabilized and the service life of switching elements Q1 to Q6 can be extended.

In this mode, the higher the battery voltage 1, the higher the value at which the rotational speed limit value (ω ^ is configured. As a result, the inverter can be controlled over a wide range of rotational speeds according to the battery voltage 1.

In this mode, in addition to the condition reported for the rotational speed of motor 4, a state in which the percentage modulation (M) is greater than the percentage modulation limit value (Mc) is also used as a condition to run the first switching control and the second switching control. As a result, a regular (normal) control of the inverter 3 can be performed up to a limit where the control diverges and the variation over which the inverter 3 can be operated in a stable manner can be expanded.

In this mode, motor controller 9 switches from an alternate execution of the first switching control and the second switching control to a regular (normal) switching control when the rotational speed (ω) of motor 4 becomes equal to or less than the limit value of rotational speed (ω ^. Thus, since regular (normal) control is resumed when the rotational speed (ω) of motor 4 decreases, the inverter system of this mode can continue to operate without shutting down. As a result , a vehicle in which an inverter device, according to this modality, is installed can continue to move.

In this mode, during the first switching control and the second switching control, the switching frequency is configured within a wide range of frequency f1 and frequency f2 so that the temperatures of switching elements Q1 to Q6 are within a range. average allowable temperature. As a result, switching elements Q1 to Q6 can be prevented from reaching an excessive temperature.

Although in the modality the switching frequency is configured in a large format 870190088447, of 06/09/2019, pg. 27/29

14/15 range of frequency f1 and frequency f2, it is acceptable to set the switching frequency f0 shown in figure 5. As a result, switching elements Q1 to Q6 can be prevented from reaching excessive temperatures.

In this mode, it is acceptable to set the switching frequency to a frequency lower than the switching frequency used during regular (normal) control when the rotational speed is equal to or below the rotational speed limit value (ωο). As a method of setting the switching frequency to a frequency lower than the frequency used during regular (normal) control, it is acceptable to use a common method in which an interruption cycle period for PWM control performed by the central processing unit Motor controller 9 CPU is extended. Or, in the interest of safety when a fault is detected, the interruption cycle period can be left in the normal period and switching over a long period can be carried out using an internal counter. In the last method, the dq axis voltage command values (Vd * Vq *) are ignored and the switching is not carried out so that the switching elements on the high side are operated with a 100% ON-task simultaneously and the low-side switching elements are operated with an ON task simultaneously from 0% repeatedly for a prescribed amount of time. In this way, the proportion of dead time for period T is decreased and the regenerative electrical charge going to battery 1 is reduced so that battery 1 overload can be prevented. Also, the switching losses of the switching elements Q1 to Q6 can be reduced and the efficiency of the inverter 3 can be improved.

In this mode, it is acceptable to configure the switching frequency so that the electrical power supplied from motor 4 to the inverter 3 due to the regeneration control of motor 4 is equal to the loss of electrical energy in the inverter 3. The loss in the inverter 3 includes losses caused by internal resistances in switching elements Q1 to Q6 and diodes D1 to D6 and the loss resulting from resistance 6.

The frequency configured in such a case will now be explained with reference to figure 7. Figure 7 is a graph of a battery 1 with charged / discharged energy versus the switching frequency characteristic in which the positive side of the vertical axis indicates charged and the side negative indicates discharged. The charged / discharged energy from battery 1 indicates an electrical energy going from the inverter 3 to battery 1. This electrical energy follows a trend in which the amount of electrical energy charged increases as the frequency increases and the amount of electrical energy discharged increases with frequency decreases. The charged / discharged energy of battery 1 is a sum of a steady state of discharged electrical energy caused by a resistor 6 and a charged electrical energy caused by a by a regenerative state occurring during periods of dead time during switching of the inverter. The charged electric energy results from Petition 870190088447, of 06/09/2019, p. 28/29

15/15 amount of regeneration is lower when the switching frequency is lower and goes to 0 if the switching is not carried out. Consequently, the charged / discharged electrical energy follows a characteristic of increasing the proportionality for the switching frequency.

Motor controller 9 sets the switching frequency to a frequency f3 (see figure 7) so that the electrical energy supplied to the inverter 3 from motor 4 matches the loss of electrical energy occurring in the inverter and the charged electrical energy / discharged goes to 0. As a result, battery 1 and inverter 3 can be electrically separated electrically from each other and battery 1 can be prevented from being subjected to an overload or an excessive discharge.

In this mode, it is also acceptable to avoid an average audible frequency (approximately 10 Hz to 20 kHz) when configuring the switching frequency. In this way, passengers and others in a region surrounding the vehicle can be protected from experiencing unpleasant noise.

While only the selected modalities have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made here without departing from the scope of the invention as defined in the attached claims. Accordingly, the aforementioned descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

Claims (12)

1. Inverter device, FEATURED for understanding: an inverter (3) including a plurality of pairs of switching elements (Q1-Q6), each of the pairs of switching elements being electrically connected to a direct current power source (1); a rotational speed detection component that detects a rotational speed of a motor (4) that is electrically connected to the switching element pair (Q1-Q6); and a control component that controls an on-off state of the switching elements (Q1-Q6) to convert direct current electrical energy from a direct current energy source (1) into an alternating current electrical energy, the control component also performs alternately a first switching control and a second switching control on the detection of a rotational speed being greater than a prescribed rotational speed. the first switching control by switching on all switching elements (Q1Q6) of the switching element pairs (Q1-Q6) connected to a positive electrode of the direct current power source (1) and switching off all switching elements (Q1 -Q6) of the pairs of switching elements (Q1-Q6) connected to a negative electrode of the direct current electric power source (1), and the second switching control connecting all the switching elements (Q1Q6) of the pairs of elements switching devices (Q1-Q6) connected to a negative electrode of the direct current power source (1) and disconnecting all switching elements (Q1-Q6) from the pairs of switching elements (Q1-Q6) connected to an electrode positive effect of the direct current electrical energy source (1). 2. Inverter device according to claim 1, CHARACTERIZED by the fact that the control component controls the switching elements (Q1-Q6) so that the time period during which the first switching control is performed is equal to the period of time during which the second switching control is performed. 3. Inverter device according to claim 1 or 2, CHARACTERIZED by the fact that the control component sets the prescribed rotational speed so that when the voltage of the direct current power source (1) becomes higher, a value at which prescribed rotational speed is set to become higher. 4. Inverter device according to claim 1 or 3, CHARACTERIZED by the fact that the control component performs the first and second switching controls alternately by determining a percentage modulation, which indicates a proportion of voltage supplied to the motor (4) in relation to current voltage 2/3 of the direct current power source (1), is greater than the prescribed percentage modulation. Inverter device according to any one of claims 1 to 4, CHARACTERIZED by the fact that the control component transitions from control alternately by performing a first and a second switching control for regular switching control upon detection of a rotational limit has become less than the prescribed rotational speed. Inverter device according to any one of claims 1 to 5, CHARACTERIZED by the fact that the control component sets the frequency at which the switching elements (Q1-Q6) are switched on and off during an alternate execution of the first and from the second switching control to a frequency lower than a frequency at which the switching elements (Q1-Q6) are switched on and off by detecting the rotational speed being equal to or less than the prescribed speed. Inverter device according to any one of claims 1 to 5, CHARACTERIZED by the fact that the control component sets the frequency at which the switching elements (Q1-Q6) are switched on and off during an alternate execution of the first and of the second switching control (Q1-Q6) so that the temperature of the switching elements is within the prescribed permissible average temperature. 8. Inverter device according to claim 7, CHARACTERIZED by the fact that the control component sets the frequency so that the temperature of the switching elements (Q1-Q6) equals the lowest temperature of the prescribed permissible temperature average. 9. Inverter device according to any one of claims 1 to 5, CHARACTERIZED by the fact that the control component sets a frequency at which the switching elements (Q1-Q6) are switched on and off during an alternate execution of the first and of the second switching control so that the electric power supply to the motor inverter (4) due to the motor regeneration control (4) to charge the battery is equal to a loss of electrical energy in the inverter. 10. Inverter device according to any one of claims 1 to 5, CHARACTERIZED by the fact that the control component sets a frequency at which the switching elements (Q1-Q6) are switched on and off during an alternate execution of the first and second switching control so that an audible frequency region is avoided. 11. Inversion control method, FEATURED for understanding: control the on-off states of a plurality of pairs of elements of 3/3 switching (Q1-Q6) electrically connected, respectively, to a direct current power source (1) so that the direct current electrical energy from the direct current energy source (1) is converted to an electrical energy alternating current and supplied to a motor (4); 5 detect a rotational speed of the motor; and alternatively perform a first switching control and a second switching control by detecting a rotational speed being greater than the prescribed rotational speed, the execution of the first switching control being carried out by connecting all 10 switching elements (Q1-Q6 ) of the pairs of switching elements (Q1-Q6) that are connected to a positive electrode of the direct current electrical power source (1) and disconnecting all switching elements (Q1-Q6) from the pairs of switching elements (Q1 -Q6) that are connected to a negative electrode of the direct current electrical energy source (1), and 15 the second switching control being carried out by switching on all switching elements (Q1-Q6) of the switching element pairs (Q1-Q6) that are connected to a negative electrode of the direct current power source (1) and turning off all switching elements (Q1-Q6) of the switching element pairs (Q1-Q6) that are connected to a positive electrode of the direct current electrical power source (1).